Automatic Day Indicator Circuit

This is Automatic day indicator circuit, by LED display each day one by one LED. Which use principal of light-activated in day with sun. To set a LDR-sensor and CD4017 acts as drive LED of 7 pcs for 7 day there.
Sometimes that we enjoy working and forget days. Which may missed important appointments. Because do not remember what day it was (Sunday – Saturday).

On Figure 1 is a simple day indicator circuit. By use a LDR (Light Dependant Resistor) Resistor values ??are transformed by light, Placed to receive light from the sun. Its resistance will partially reduce until a transistor-Q1 conducting. Then send a output signal passed to R2 that acts as to a Shaping circuit. To send both impedance of both channels better. By there are a capacitors-C2 as the input clock signal generator to IC1. Which in no light at night, this input voltage will be 0 volts.

The Automatically Day indicator circuit
Figure 1 The Automatically Day indicator circuit

The first output of IC1 is pin Q0 that will drive LED1 to display as first day that is Sunday. Each day there will be only one LED lights only. The LED on the left will be divided voltage to 0V equally well by R4-resistors. The potentiometer-VR1 is used to adjust the sensitivity. And capacitance value of C1 to the circuit smoothly.

The switch-S1 is used to set a date to match when the user first. This circuit works with DC adapter 9-12V.

How to build this project.
This project is a few components so can put in an universal PCB board. So, the wiring and various parts can view of the example in Figure 2. So be carefull for the polarity of the electrolytic capacitors, transistor correctly and so Pin of the IC-4017 is not error.

Figure 2 the components layout and wiring of this projects.

The components List

Resistors ¼ W +5%
R1: LDR___number__ORP12
R2: 1K
R3: 10K
R4: 470 ohms
VR1: Potentiometer 20K
C1: 470uF 16V, Electrolytic
C2: 22uF 16V, Electrolytic
IC1: CD4017 Decade counter with 10 decoded outputs IC
Q1: BFY51, NPN transistors
LED1-LED7: LED as you want to see.
Others, Limit switch, DC adapter…etc.


BY51 pinout
Q1-BY51 Pinout and datasheet

Sharing is caring!

JLCPCB - Only $2 for PCB Protytpe(Any Color)

With 600,000+ Customers Worldwide, 10,000+ PCB Orders Per Day

Up to $20 shipping discount on first order now:

Related Posts


I always try to make Electronics Learning Easy.

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.

newest oldest most voted
Notify of

How to automatic change tha day pls expanded…

Close Menu